Telephone-relay.



No. 658,30I. l Patented Sept. I8, |900. W. G. URMSON.

TELEPHONE RELAY.

. (Application led Feb. 5, 1900.)

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No. 658,30l. Patented sept. I8, |900l w. G. uRMsoN. Y

TELEPHONE RELAY.

(Application led Feb. 5, 1900.)` (No Model.) 2 `Sheets-Sheet 2.

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' Unirtrnn STATES PATENT Ormea.

WILLIAM G. URMSON, OF NEW BRUNSVICK, NEW JERSEY, ASSIGNOR OFTHREE-FOURTHS TO JOHN W. PARSONS, HENRY A HULL, AND JOSIAH TICE, OF SAMEPLACE.

-TELEPHONE-RELAY.

SPECIFICATION forming part of Letters Patent No. 658,301, datedSeptember 18, 1900. Y

Application led February 5, 1900. Serial No. 4,060. (No model.)

Io all whom t may concern.-

Be it known that I, WILLIAM G. URMsoN, a citizen of the United States,and a resident of New Brunswick, in the county of Middlesex and State ofNew Jersey, have invented certain new and useful Improvements inTelephone-Relays,of which the following is a specification.

The object of my invention is to construct a telephonie repeaterwhichshall actin all respects as does a telegraph-repeater and which wheninserted between the terminals of a telephone-line will repeat inamplified form telephonie currents arriving from either direction andwill send them out in such amplied form in the opposite direction.

Myinvention mayalso be used as a boosterthat is to say, as an instrumentwhich is inserted in a bridge across the telephone-circuit between thetelephone terminal stations and which operates on the current which hasarrived from the transmitting-station and sends out such currents inamplified form to the receiving-station.

I have discovered that in tele phonic repeaters a microphone which isadjusted by tension as distinguished from compression and which has anair-space between the electrode gives altogether remarkable andstrikingr results. I refer, for instance, to such a microphone as isshown in the Patent No. 557,588 to Lockwood. The characteristic of suchmicrophone is to be found in the fact that the electrodes are separatedby an air-space, but are surrounded by granular material, the electrodesbeing held apart by suitable tension devices acting on the plates. ordiaphragms to which they are secured. Motionl of the electrodes towardor from each other tion lies in the fact that I use electromagnets onthe opposite sides of the microphone and combine such electromagnetseach with an induction-coil the primaries of which are connected in acommon local-battery circuit including the' microphone. As will be eX-plained later on, I secure hereby not only the double action of twoelectromagnets on a common microphone, but also a building-up effect ofthe current through the inductioncoils and microphone. I may mount theelectromagnets on the opposite poles of a permanent magnet, and thus actto increase and decrease the inherent magnetism of the poles by thetelephonie currents.

So, too, I may use a pair of magnets on each pole and connect themoppositely in pairs.

' Aside from the electrical features to which I have above referred myinvention relatesv to certain improved mechanism by which I secure theadjustment at the proper tension of the electrodes of the microphonewhich are separated by an air-space. It is necessary for properoperationthat these electrodes `be adjusted to a very precisely determined Atsuch'l position-a critical point of poise. position of adjustment themicrophone will act with great force and snap. The means `of adjustmentwhich I have invented permit In Fig. l there is a permanent horseshoe--f magnet N S, on the poles of which are mounted two electromagnets ff.Between these electromagnets and on a baseplateA there is secured in anyconvenient manner a microphone com-posed of two ele'ctrodesa a,eachattached to diaphragms b b, which are preferably of mica, saiddiaphragm being surrounded by an annular shell c, which parts inclose anamount of granular material d, which is, however, not permitted to fallinto the space between the electrodes. The electrodes are held apart ata very precisely determined position of adjustment by suitable tensiondevices as distinguished from compression devices, a preferred form ofwhich tension devices will be described later on. Soft-iron armatures eare secured to the diaphragms or the electrodes. The pole-pieces of theelectromagn ets ff', acting on the armatures e, tend to pull thediaphragms apart. This tendency is balanced by the tension devices.- Itwill therefore be seen that under normal conditions the electrodes ofthe microphone are in a very delicate position of poise and at whatmight be called a critical point of poise, so that the slightestvariation inthe electromagnetic force of the pole--pieces will producemost pronounced effects.

While I prefer the construction of microphone above described, I mayalso use such similar construction as is described in Lockwoods patent,No. 528,640, of November 6, 1894:, and where it is not especiallymentioned in the claims other types of microphones may also be employed,but not with such good effect. Y

The line l passes through the fine-wire secondary 2 of an induction-coill0, through the electromagnet f, and back to the original stations or toground. The line-Wire 3 passes through the fine-Wire secondary 4 of aninduction-coil ll, thence through the electromagnetf, and back to thestation from which the line carne or else to ground. The local circuit8, in which is found the battery 7, contains two primaries 5 6, shown asin series with each other, which cooperate, respectively, with thesecondaries 4 2 in the lines 3 l. As is well understood, the phase ofthe current coming over the line l and passing through the secondarycoil 2 is one hundred and eighty degrees apart from the phase of thecurrent which is thereby generated in the primary coil o'. The phase ofthe current in the coil 6 is the same as the phase in the coil 5, andthis again is one hundred and eighty degrees apart from the phaseinduced in the coil 4. It follows that the phase of the current in thecoil 2 of the line l is the same as the phase of the current in the coilL of the line 3. It is to be noted that the local-battery circuit Spasses not only through the primaries 5 6 of the induction-coils 1011,but also through the microphone-electrodes a, aand the granularmaterial cl surrounding them. The electromagnetsff must act inconjunction-that is, both electromagnets must act to pull apart theelectrodes at the same time. Since the phase of the currents in theseelectromagnets is the same, as I have above explained, and since theseelectromagnets have pole-pieces which are of opposite polarity, it istherefore necessary that the windings of these electromagnets should beoppositely connected, and this is indicated in the drawings. When thecurrent comes over the line l and passes through the electromagnet f,the current which is induced by means of the two induction-coils l0 llinto the electromagnet f will cause both of these magnets to act.simultaneously either to increase their magnetismsI to simultaneouslypull the electrodes apart or to decrease their magnetisms to allow theelectrodes to move together. In either case the variation of theresistance brought about in the local circuit 8 by the operation of themicrophone will act to reinforce the variation of current alreadybrought about in the local circuit by the inductive action of theinduction-coils 10 l1. Thus it' there be an increase of the current inthe line l and electromagnetf, which by the inductive action of the coillO will generate a decreasing current in the local circuit 8, the sameincrease of current in the electromagnetf will act to pull apart theelectrodes a to increase ,the resistance of the microphone and todiminish the current owing in the local circuit. I thus get by theaction of the microphone and its operating-magnets and theinduction-coils what I term a building-up effect, which is most markedand striking and which adds much to the eficiency of my repeater.

It is clear that the action of the arrangement shown in Fig. l isreversible. Weak telephoniecurrents which arrive over the line l areconverted into strong telephonie currents which depart over the line 3;but at the same time weak telephonie currents which arrive over the line3 may be converted into strong telephonie currents which go out on theline l.

While I have shown a single electromagnet on each side of themicrophone, it is clear that a pair of electromagnets might be usedinstead of a single electromagnet. Such magnets might be connected inparallel or in series, or the magnetfon the north pole of thehorseshoe-magnet might be connected in series, but in the oppositedirection, with a magnet on the south pole of the horseshoemagnet. Suchmanifest variations in the number of magnets employed and theirconnections manifestly fall within the scope of my invention.

The arrangement shown in Fig. 2, which is of the booster type,will needbut little additional explanation. We have the same microphone, thehorseshoe-magnet N S, the electromagnets ff', mounted thereon, theinduction-coils 10 1l, and the local circuit 8, with a battery 7. Inthis system, as in that of Fig. l, current passing through coil f, whichacts to increase the north magnetism of its core, corresponds to currentpassing through the magnet f', which acts to increase the southmagnetism of its core. This means that the connection of the bridge-linewith the electromagnets ff must be such as to pass the currentoppositely through the windings of these magnets. The current in thesecondary 2 is in the same phase with the current in the secondary 4L.The current in the primaries 5 and 6 is one hundred and eighty degreesapart in phase from the current in the IOO IIO

secondaries. It will be seen, therefore, that the conditions of thecircuit arrangements of Fig. l are substantially reproduced. An increaseof current in the bridge-wire and secondaries 2 4 causes a pulling apartof the electrodes of the microphone and a consequent decrease of thecurrent in the local circuit 8. This builds up with a decrease ofcurrent in said local circuit,brought about b'y the inductive action ofthe induction-coils which is in proper phase therewith. I layparticular'stress 4upon the fact that the secondaries 2 and 4 are in abridge-wire across the telephone-circuit and are not in series in thetelephone-line. The resistance to the telephonie current is therebyreduced.

In Figs. 3 and 4 I show a means for adjusting to the point of criticalpoise a series of microphones of the type which I prefer to ernploy.There is a pair of brackets jj', having arms jz, which are supported onshort stiff spiral springs k. In this manner the brackets jj aresupported with a reasonable amount of rigidity and are capable of movingback and forth under the action ofthe electromagnets ff. The microphonesT are preferably of the construction which I have before described. Theyare supported each between the opposite arms of an oval elastic springZ. This spring has a definite position of rest to which it tends toreturn. Short screws are secured to the centers of each of thediaphragms of the microphone. The screws on one set of diaphragms passthrough apertures in the oval or other-shaped spring Z and are securedto them by nuts frt. In order that the microphone may not beshort-circuited by the spring Z, I use insulating material between thenuts n, screws, and springs Z. Thumb-nuts o,acting on the screws of theother set of diaphragms, serve to regulate the tension of the springs Z,and thus the tension of the diaphragnis 'of the microphones. One set ofscrews is secured to the arms of the bracket on one side of theapparatus,and the other set of screws is secured to the arms of thebracket j on the opposite side of the microphone. Armatures e aresecured to the brackets jj'. It is clear when the electromagnels ff' areenergized the brackets jj are pulled in opposite directions and thediaphragms of the microphones are pulled apart. When the magnetism ofthe electromagnets ff decreases,the diaphragms of the microphone aremoved toward each other by the resiliency of the oval springs Z.

The point of the construction which has just been described is thefunction which it possesses of enabling a series of microphones, whichare connected in series or parallel in a circuit, to have the tension oftheir respective electrodes readily adjusted each independent of theother and without interfering with the other. I have previouslyemphasized the fact that there is a particular position of poise atwhich the action of these microphones is most pronounced.

It is necessary to adjust the microphones to this position of tension orpoise. The arrangement shown in Figs. 3 and 4 enables this to be donewith great. readiness. Y.

In order to adjust the microphone 'ro the critical point of poise, Iproceed as follows: I adjust the microphone with the tension devices andascertain its sensitiveness by touching it or by talking or breathingagainst the variable resistance, a telephone-receiver having beeninserted in the line l 1 or in theline 3 3. The pole-pieces s s are then-moved to or from the armatures e e until a singing is heard in thereceiver, this being a position of equipoise between the pull of thetension devices and the opposing pull of `the electromagl net. Theequipoise is then destroyed, and the critical point of poise is found bymoving the pole-pieces slightly either way until the singing ceases. Theequipoise is thus destroyed and a critical point of poise is foundthatis, a position where the impulses given by the pole-pieces are repeatedand am plitied; but there is no singing, because the operation effectedbetween the tension devices and the pole-pieces is no longer automatic,but must be produced by an outside force, as from the transmittinginstrument in circuit with the coil around the pole-piece. The very ampli- Liication and building up of theim pulses which produces thesinging at the position of equigether and adjusts the diaphragms of theini-A crophone. to the proper position. Armatures e coact with theelectromagnets. l

The results which have been attained with the electrical apparatusdescribed in this application have been remarkable, and conversation hasbeen carried on overan amount of wire much greater than was heretoforepossible.

For convenience I shall use the term telephonic relay27 to apply both tothe repeater construction of Fig. l and to the booster construction ofFig. 2, so I use the word microphone to cover any suitable variableresistance. Y

There are some connections in which vI should not use ne wire for mycoils2 4. Thus I may use magneto-transmitters at the subscribersstations and dispense with the batteries at these stations. In this"case my repeater would be at the central office and there would beswitching devices to switch the calling-subscriber to the line-circuitgoing to one side of the repeater and the called subscriber IIO to theline-circuit going to the other side of the repeater. In such caseitwill be advisable to reduce the line-resistance by not having highresistance or fine wire in the coils 2 4.

Vhat I claim is-r 1. A telephonie relay comprising the combination of amicrophone having electrodes separated by an air-space, conductingmaterial surrounding the electrodes, tension devices for holding theelectrodes in a position of poise and an elcctromagnet for varying theaction of the tension devices, substantially as described.

2. A telephonie relay comprising the combination of electrodes separatedby an air-' space, granular material surrounding and bridging theelectrodes, tension devices for holding the electrodes in a position ofpoise and an electromagnet for acting on the tension devices to vary thecurrent iu the microphone, substantially as described.

3. A telephonie relay comprising the cornbination of a microphone,coacting electromagnets on opposite sides thereof, secondary coils incircuit with each electromagnet and primary coils, cooperating with thesecondary coils, in a common local circuit, substantially as described.

4. A telephonie relay comprising the combination of a microphone havinga pair of electrodes separated by an air-space, conducting materialsurrounding the electrodes, tension devices for .holding the electrodesin a position of poise, coacting electromagnets situated on oppositesides of the microphone, secondary coils in circuit with eachelectromagnet and primary coils, cooperating with the secondary coils,in a common local circuit, substantially as described. l

5. A telephonie relay comprising the combination of a microphone, abipolar permanent magnet and coacting electromagnets mounted on thepoles thereof and acting on the opposite sides of the microphone,substantially as described.

6. A telephonie relay comprising the combination of a microphone, abipolar perma nent magnet, coacting electromagnets mounted on the polesthereof and acting on the op posite sides of the microphone,secondarycoils in circuit with each electromagnet and primary coils, coperatingwith the secondary coils, in a common local circuit, substantially asdescribed.

7. A telephonie repeater comprising the combination of a microphone,coacting electromaguets on the opposite sides thereof, secondary coilsin circuit with each electromagnet and the incoming and outgoing linesre spectivcly and primary coils,coperatin g with the secondary coils, ina common local circuit, substantially as described.

S. A telephonie relay comprising the combination of a microphone havinga pair of electrodes separated by an air-space, conducting materialsurrounding the electrodes, tension devices for holding the electrodesin a position of poise, a bipolar permanent magnet and coactingelectromagnets mounted on the poles thereof and acting on the oppositesides of the microphone, substantially as described.

9. In a telephone-relay, a microphone having a pair of separatedelectrodes, conducting material surrounding the electrodes, springarmsand adjustable devices for securing the electrodes to the spring-arms ina position of poise, substantially as described.

l0. In a telephone-relay, a microphone hav-` ing a pair ofelectrodes,spring-arms surrounding the microphone and adjustable devicessecuring the electrodes to the opposite arms, substantially asdescribed.

ll. In a telephone-relay, a microphone having electrodes, a spring,having one arm secured to one electrode,and a screw and thumbnutforadjustably securing the other electrode to the other arm in aposition of poise, substantially as described.

l2. In a telephone-relay, a pair of brackets having arms, springs onWhich the brackets are supported and a series of microphones supportedrespectively between opposite arms of the brackets, substantially asdescribed.

13. In a telephone-relay, a pair of brackets having arms,supportingdevices for the brackets,a series of microphones,a spring surroundingeach microphone having its opposite arms adjustably secured to theelectrodes thereof, and connections between the bracket-arms andelectrodes, substantially as described.

14. In a telephone-relay, a pair of brackets havin g arms,supportin gdevices for the brackets,a series of microphones having screwsprojecting from its opposite electrodes, a spring surrounding eachmicrophone having one arm rigidly connected to one screw and the otherarm adjustably connected tothe other screw, and connections between thebracket-arms and the screws, substantially as described.

In testimony whereof I have signed my name to this specification in thepresence of two subscribing Witnesses.

WVM. G. URMSON.

Witnesses:

WM. A. GROBEN, JOHN FLoRANoE.

IIO

